The present invention relates to structural members and methods for making the same. In particular, the present invention relates to cored metal contoured parts and methods for making the same.
In recent years there has been an increasing emphasis on the use of lightweight materials. One application, for example, has been their use to improve the efficiency of motor vehicles. To that end, the United States Government and the U.S. Council for Automotive Research (USCAR)xe2x80x94which represents Daimler Chrysler, Ford, and General Motors have partnered to form the Partnership for a New Generation of Vehicles (PNGV). One goal of PNGV is to develop technology that can be used to create environmentally friendly vehicles with up to triple the fuel efficiency, while providing today""s affordability, performance and safety. For example, PNGV wants to improve the fuel efficiency of today""s vehicles from about 28 miles per gallon (mpg) to about 83 mpg and a 40-60% decrease in the present curb weight (3200 pounds).
One method to improve the fuel efficiency is to decrease the weight of today""s vehicles and use lighter weight materials. The materials used in today""s vehicles, such as steel and aluminum, are quite heavy relative to light-weight materials such as composite materials, but have been necessary to provide sufficient structural properties, including tensile, compression, flexural, interlaminar shear, and in-plane shear strengths and other mechanical and material properties, to meet vehicle design requirements.
One way to increase the structural properties of materials, particularly the torsional or flexural strength, is to make them in a more structurally efficient form. In one structurally efficient form, metals like aluminum and steel have been combined with a supporting structure, such as a honeycomb core material, by sandwiching the honeycomb between panels of the metal. Examples of such combinations have been described in U.S. Pat. Nos. 4,291,205, 5,140,913, 5,192,623, 5,635,306, 5,875,596, and 5,899,037, the disclosures of which are incorporated herein by reference. Such combinations, however, have been limited to relatively flat structures and so their end use has been quite limited.
The present invention provides contoured metal-containing structural members and methods for making the same. The contoured structural members comprise metal-containing materials sandwiching a support or stabilizing structure. The contoured structure can be provided by tube rolling (or roll wrapping) the metal-containing materials and the support structure together and then, if necessary, bonding them or connecting them. With a contoured and generally non-flat structure, applications for the structural members of the present invention are nearly limitless.